Byssinosis is a disease of textile workers that is attributed to the action of cotton dust on the lung. Although cotton dust contains a mixture of substances, the major compound(s) causing byssinosis appear to be contained in the bracts which constitute the major component of ground plant matter found in ginned cotton. We have identified biological responses to two fractions of aqueous extracts of cotton dust (CDE) and cotton bracts (CBE). One fraction contains a low molecular weight compound that causes powerful contractions of smooth muscle in the airways and pulmonary vessels. Another fraction contains a condensed polyphenol (tannin) that causes release of 5-HT, ADP, and TxA2 from bovine and human platelets as well as aggregation of these platelets. These studies into the causes of byssinosis will be continued by examining the effects of CDE and CBE as well as various fractionation products of these extracts on: (1) smooth muscle contractility of isolated canine airways and pulmonary vessels, (2) the release of 5-HT, Beta-thromboglobulin, Beta-NAGAse, and TxA2 from human platelets and aggregation of these platelets, (3) the release of a neutrophil chemotactic factor from guinea pig and human alveolar macrophages and canine traheal epithelial cells, and (4) the electrophysiologic properties of the canine tracheal epithelium. CDE will be obtained from a "standard" cotton mill dust as well as dusts that have been found to be "active" and "inactive" in producing changes in pulmonary function in human volunteers participating in experimental cardroom study at Clemson. CBE will be obtained from several varieties of cotton in order to examine the temporal, regional, and cultivar variations that occur in the smooth muscle and platelet activating factors. The effects of a "standard" endotoxin from Enterobacteria Agglomerans (a known contaminant of cotton) on smooth muscle, platelets, macrophages, and tracheal epithelium also will be investigated. The bioactivity of these compounds might well be important in the pathogenesis of byssinosis and characterization of their mechanisms of action could foster new approaches to the management of this disease.